Chinese display in the image function

Convert GB code to utf8,php TTF supports UTF8 encoded non-ASCII character output. After analyzing this code, we find that the mixed output image of Chinese and ASCII can be realized, which makes it more convenient for us to manipulate the image function.
The code is as follows:
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function Gb2utf8 ($GB)
{
if (!trim ($GB))
return $GB;
$filename = "Gb2312.txt";
$tmp =file ($filename);
$codetable =array ();
while (list ($key, $value) =each ($tmp))
$codetable [Hexdec (substr ($value, 0,6))]=substr ($value, 7,6);

$utf 8 = "";
while ($GB)
{
if (Ord (substr ($GB, 0,1)) >127)
{
$this =substr ($GB, 0,2);
$GB =substr ($GB, 2,strlen ($GB)-2);
$utf 8.=u2utf8 (Hexdec ($codetable [Hexdec (Bin2Hex ($this)) -0x8080]);
}
Else
{
$this =substr ($GB, 0, 1);
$GB =substr ($GB, 1,strlen ($GB)-1);
$utf 8.=u2utf8 ($this);
}
}

/* $ret = "";
for ($i =0; $i <strlen ($utf 8); $i +=3)
$ret. =CHR (substr ($utf 8, $i, 3));

return $ret; *

return $UTF 8;
}
function U2utf8 ($c)
{
/*for ($i =0; $i <count ($c); $i + +) * *
$str = "";
if ($c < 0x80) {
$str. = $c;
}
else if ($c < 0x800) {
$str. =CHR (0xc0 | $c >>6);
$str. =CHR (0x80 | $c & 0x3F);
}
else if ($c < 0x10000) {
$str. =CHR (0xe0 | $c >>12);
$str. =CHR (0x80 | $c >>6 & 0x3F);
$str. =CHR (0x80 | $c & 0x3F);
}
else if ($c < 0x200000) {
$str. =CHR (0xF0 | $c >>18);
$str. =CHR (0x80 | $c >>12 & 0x3F);
$str. =CHR (0x80 | $c >>6 & 0x3F);
$str. =CHR (0x80 | $c & 0x3F);
}
return $str;
}
?>


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Header ("Content-type:image/jpeg");
$im = imagecreate (800, 400);
$black = imagecolorallocate ($im, 0, 0, 0);
$white = Imagecolorallocate ($im, 255, 255, 255);
Include ("gb2utf8.php");
$str =gb2utf8 ("AAA 32434");
Imagettftext ($im, $white, "/USR/SHARE/FONTS/DEFAULT/TRUETYPE/SIMSUN.TTC",
$STR);

Imagejpeg ($im);
Imagedestroy ($im);

?>